Method of making separators



Patented Aug. 9, 1932 UNETD WILLIAM s. GOULD, on NEW YORK, AND WILLARD :B. OSBORNE, or BUFFALO,

* NEW YORK V 7 METHOD OF MAKING SEPARATOBS No Drawing.

This application is carved out of the application on which Patent No. 1,666,007 was granted April 10th, 1928, to lVilliam S. Gould and Willard B. Osborne, and filed after the grant of said patent.

It has long been the. desire of storage bat tery manufacturers to produce a battery with treated separators which can be shipped dry. The difliculty heretofore experienced has been that if the treated separators be dried before placing in the battery they split or curl to such an extent that they become destroyed, or at least greatly injured, in the assembly of the battery elements. f such separators be placed in the battery in a damp condition the action is detrimental to the positive plates. It is customary to treat wooden separators with an alkali to remove the constituents detrimental to the storage battery but heretofore no known means has been discovered for effecting suflicient drying of the separators after such alkali treatment to permit them to be assembled in a battery without curling or warping. In said parent application above identified, we have disclosed a method of drying the wooden separators so that they will not curl or warp.

It is the principal object of the present invention to provide a separator formed of wood and impregnated with a substance inert to the electrolyte and which, whether given the alkali treatment or not, is treated not only to prevent curling or warping but to give additional mechanical strength which will greatly lessen the loss due to breakage in handling and assembly.

A more specific object of the invention is to provide a wooden separator impregnated with rubber, for instance by the method disclosed in the patent numbered 1,194,818 and granted to Rufus N. Chamberlain, the separator being subsequently given a specifically applied heat treatment which will vulcanize, or else harden without truly vulcanizing, the rubber and consequently increase the mechanical strength without entirely destroying the necessary porosity.

In carrying out the invention we take a suitable wood, such as Port Orford white cedar in the form of boards or veneer and Application filed April 28,

1928. Serial No; 273,765.

immerse it in a solution of approximately three per cent (3%) caustic soda at a temperatureof approximately 212F. for about eight hours, The wood is then removed from this solution and washed in-clear running water for, say, fourteen hours to remove the caustic soda. Any residual soda may then be neutralized by placing the wood in a weak solution of sulphuric acid of about 1.02 specific gravity. A subsequent washing for about two hours is resorted to to effect thorough removal of the chemicals. Whether or not the wood has been subjected to this chemical treatment it is impregnated with rubber for instance by the means disclosed in said Chamberlain patent and is then ready for the next step which consists in or comprises putting it through a drying machine of any desired detailed mechanical construction but preferably having a series of movable steam heated, horizontal iron plates which rest against the opposite surfaces of the wood, these iron plates being heated sufficiently to effect a rapid but thorough drying of the wood. The plates hold the wood fiat and are preferably so arranged as to apply a slight pressure thereto so that the wood is prevented from curling-or warping and splitting. Apparently, the drying of the rubberized wood between the heated plates either partially vulcanizes the rubber, or else hardens it without truly vulcanizing, and as a result the mechanical strength is increased without substantially changing or at least destroying the natural porosity and permeability of the wood. 7

After the stock is thus treated and dried it is grooved and cut to the desired length in the ordinary way to form separators of the required size and thickness. Such separators may be stored, handled and otherwise used in the same manner as untreated wood separators, that is to say they may be handled, shipped and assembled in dry condition without danger of curling or warping.

Having thus described the invention, we claim:

1. The method of making a dry flat separator from wood as a base, comprising treating the wood to remove substances deleterious to storage batteries, applying rubber tothe Wood, maintaining the wood fiat and subjecting it to pressure, and simultaneously applying heat to the opposite surfaces of the wood to harden the rubber, the heating being discontinued while the wood still retains porosity.

2. The method of making a dry flat separator from wood as a base, comprising treating the wood toremove substances deleterious to storage batteries, applying rubber to the wood, maintaining the wood flat and subjecting it to pressure, and vulc'anizing the rubber to eflect hardening thereof without destroying the natural porosity of the wood.

In testimony whereof we aflix our signa-. tures. I p WILLIAM S- GOULD- WILLARD B. OSBORNE. 

